The present invention concerns a hinge for a seat, in particular for an automobile vehicle, and a seat provided with said hinge.
One prior art hinge for a seat, in particular for an automobile vehicle, is of the type comprising:
at least one connecting flange adapted to be fixed to a seat cushion or squab and one support-flange that can be attached to the cushion and/or to the squab, the flanges being mounted to rotate relative to each other about a hinge axis that is substantially perpendicular to them, and PA1 at least one lever for coupling the flanges together having a first end mounted to pivot on the support-flange about a pivot axis substantially parallel to the hinge axis so that the coupling lever can pivot between a position in which a second end of the lever is attached to the connecting flange by virtue of cooperation of complementary shapes and a position in which said second end is released. PA1 the immobilising means comprise two complementary immobilising ramps respectively carried by the support-flange and by the second end of the coupling lever, the ramps being separated when the coupling lever is in the attached position, and PA1 a weakened area of the support-flange adapted to deform when the flanges are subjected to the accidental torque to enable movement of the coupling lever relative to the support-flange until the immobilising ramps come into contact and cooperate to immobilise the second end of the coupling lever in the position attached to the connecting flange; PA1 the pivot axis of the coupling lever is defined by a pivot carried by the first end of said lever pivoting in a pivot slot in the support-flange and the weakened area includes a portion of the support-flange extending between the pivot slot and a weakening slot in the support-flange near the pivot slot and between the pivot slot and the immobilising ramp carried by the support-flange; PA1 the coupling lever is generally arcuate, the inside contour of the lever including a notch for weakening the lever so that, if the immobilising ramps cooperate by virtue of by an accidental torque, the coupling lever is deformed by alteration of its curvature; PA1 the hinge includes another flange for connection to the squab or the cushion and at least one other lever for coupling the support-flange to said other connecting flange, the support-flange being housed between the two connecting flanges, the two coupling levers being respectively hinged to two opposite faces of the support-flange; PA1 the two connecting flanges are respectively adapted to be fixed to the cushion and to the squab, the hinge further comprising means for manoeuvring the coupling levers between a rest configuration in which all the coupling levers are attached to their corresponding connecting flange to couple the latter and to immobilise the squab relative to the cushion and two alternative active configurations in which only one of the coupling levers is attached to its corresponding connecting flange to enable adjustment of the inclination of or temporary folding forward of the squab, as appropriate; PA1 the hinge comprises a pair of coupling levers associated with each connecting flange and disposed substantially symmetrically relative to the hinge axis, the four coupling levers being hinged alternately to the two faces of the support-flange and to sectors of the support-flange offset parallel to the hinge axis, each immobilising ramp carried by the support-flange being on a sector of the support-flange adjacent a sector to which is hinged the coupling lever carrying the complementary immobilising ramp.
FR-A-2 722 150 (FR-94 08 297) corresponding to U.S. Pat. No. 5,590,931 describes a hinge of the above type, for an automobile vehicle seat, in which the coupling lever is placed in the connecting flange attachment position by means of a manoeuvring cam cooperating with a wedging effect with a wedging cam formed in the lever.
In the event of an impact to the vehicle causing a violent longitudinal force to be exerted on the seat squab, the flanges of the hinge are subject to a high torque that can accidentally separate them.
This occurs in particular if the accidental torque is exerted against the wedging effect holding the manoeuvring and wedging cams in contact.